Surgical Correction of Unicoronal Synostosis: Fronto-Orbital Distraction versus Calvarial Switch

Background: There is a need for a new, less-invasive surgical option for unicoronal synostosis (UCS). The aim of this study was to compare the resulting morphology and symmetry in patients with UCS after fronto-orbital distraction (FOD) or calvarial switch (CS). Methods: A total of 79 patients with isolated UCS operated on between 2005 and 2021 were analyzed. Follow-up was until 3 years of age. Angles describing orbital dystopia and anterior cranial fossa deviation and cant were measured. Key linear dimensions, cranial cavities, and indices were calculated. Results: A total of 66 patients were included (14 in the FOD group and 52 in the CS group). The 3-year follow-up revealed significant improvement in all angles in both groups, with significant superiority in orbital dystopia correction after FOD (median improvement of 5.7 degrees as compared with 3.3 degrees after CS). In addition, nasal and orbital volumes tended to be smaller, especially after CS; however, FOD resulted in a smaller absolute difference in orbital volume. Asymmetry in the orbital, nasal, and sphenoid regions also improved at the 3-year follow-up in both groups, although FOD resulted in normalization of the affected orbital shape and significantly improved overall asymmetry relative to that observed in the CS group. Conclusions: This study found that FOD achieves superior overall symmetry, as well as better shape correction of the cranium, as compared with CS, while also being less invasive. These findings suggest FOD as a safe and effective alternative to correct UCS and, possibly, the preferred surgical method.